Should Parameter Maps refer to the fno:Parameter IRI or its fno:predicate?

[jduchateau]

Should a Parameter Map refer to the IRI of the fno:Parameter instance itself, or to its associated fno:predicate?

The test cases currently do not agree on this. For grel functions, the parameter maps mainly (and probably always) refer to the parameter instance definition. However, for idlab-fn functions, they refer to the fno:predicate. This creates ambiguouity not knowing if RML Processor need to support one or the other or both as synonyms.

The spec briefly states:

A Parameter Map: a Term Map that MUST generate a named node. That named node specifies the referenced Parameter.

And "Parameter" links to:

A Parameter: an input parameter of a Function.

Example

In test case 2, it refers to the parameter definition grel:valueParam, not its predicate grel:valueParameter:

    rml:function grel:toUpperCase ;
    rml:input
        [
            rml:parameter grel:valueParam ;
            rml:inputValueMap [
                rml:reference "Name" ;
            ]
        ] .

grel:toUpperCase
    a                   fno:Function ;
    fno:name            "to Uppercase" ;
    rdfs:label          "to Uppercase" ;
    dcterms:description "Returns the input with all letters in upper case." ;
    fno:solves          grel:prob_ucase ;
    fno:expects         ( grel:valueParam ) ;
    fno:returns         ( grel:stringOut ) .

grel:valueParam
    a             fno:Parameter ;
    fno:name      "input value" ;
    rdfs:label    "input value" ;
    fno:predicate grel:valueParameter ;
    fno:type      xsd:string ;
    fno:required  "true"^^xsd:boolean .

However, in test case 3, it refers to the predicate idlab-fn:str, rather than the parameter definition idlab-fn:_str:

    rml:function idlab-fn:toUpperCaseURL ;
    rml:input
        [
            rml:parameter idlab-fn:str ;
            rml:inputValueMap [
                rml:reference "url"
            ];
        ] .

idlab-fn:toUpperCaseURL
    a                   fno:Function ;
    fno:name            "toUpperCaseURL" ;
    rdfs:label          "toUpperCaseURL" ;
    dcterms:description "Returns an uppercase, valid url." ;
    fno:expects         ( idlab-fn:_str ) ;
    fno:returns         ( idlab-fn:_stringOut ) .

idlab-fn:_str
    a             fno:Parameter ;
    fno:name      "input string" ;
    rdfs:label    "input string" ;
    fno:type      xsd:string ;
    fno:predicate idlab-fn:str .